Water from a wave or that is splashed may enter a top opening of a breathing tube of a snorkel when used for snorkeling or diving. To solve this problem, the top opening is typically bent and a louver-like member (i.e., splash prevention device) is provided on the mouth of the top opening. To be effective a splash prevention device should have the following features: (i) prevent splashed water from entering the breathing tube of a snorkel while permitting a free passage of air during use, (ii) be compact; (iii) should not obstruct a flow of air for breathing; and (iv) have a low manufacturing cost. Currently, snorkels with a splash prevention devices do not have all of these features. Therefore, improvements in splash prevention devices for snorkels are constantly being sought.